/* ----------------------------------------------------------------------
 * Project:      CMSIS DSP Library
 * Title:        arm_mult_q15.c
 * Description:  Q15 vector multiplication
 *
 * $Date:        18. March 2019
 * $Revision:    V1.6.0
 *
 * Target Processor: Cortex-M cores
 * -------------------------------------------------------------------- */
/*
 * Copyright (C) 2010-2019 ARM Limited or its affiliates. All rights reserved.
 *
 * SPDX-License-Identifier: Apache-2.0
 *
 * Licensed under the Apache License, Version 2.0 (the License); you may
 * not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an AS IS BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "arm_math.h"

/**
  @ingroup groupMath
 */

/**
  @addtogroup BasicMult
  @{
 */

/**
  @brief         Q15 vector multiplication
  @param[in]     pSrcA      points to first input vector
  @param[in]     pSrcB      points to second input vector
  @param[out]    pDst       points to output vector
  @param[in]     blockSize  number of samples in each vector
  @return        none

  @par           Scaling and Overflow Behavior
                   The function uses saturating arithmetic.
                   Results outside of the allowable Q15 range [0x8000 0x7FFF] are saturated.
 */
#if defined(ARM_MATH_MVEI)

#include "arm_helium_utils.h"

void arm_mult_q15(
	const q15_t *pSrcA,
	const q15_t *pSrcB,
	q15_t *pDst,
	uint32_t blockSize)
{
	uint32_t  blkCnt;           /* loop counters */
	q15x8_t vecA, vecB;

	/* Compute 8 outputs at a time */
	blkCnt = blockSize >> 3;
	while (blkCnt > 0U) {
		/*
		 * C = A * B
		 * Multiply the inputs and then store the results in the destination buffer.
		 */
		vecA = vld1q(pSrcA);
		vecB = vld1q(pSrcB);
		vst1q(pDst, vqdmulhq(vecA, vecB));
		/*
		 * Decrement the blockSize loop counter
		 */
		blkCnt--;
		/*
		 * advance vector source and destination pointers
		 */
		pSrcA  += 8;
		pSrcB  += 8;
		pDst   += 8;
	}
	/*
	 * tail
	 */
	blkCnt = blockSize & 7;
	if (blkCnt > 0U) {
		mve_pred16_t p0 = vctp16q(blkCnt);
		vecA = vld1q(pSrcA);
		vecB = vld1q(pSrcB);
		vstrhq_p(pDst, vqdmulhq(vecA, vecB), p0);
	}
}

#else
void arm_mult_q15(
	const q15_t *pSrcA,
	const q15_t *pSrcB,
	q15_t *pDst,
	uint32_t blockSize)
{
	uint32_t blkCnt;                               /* Loop counter */

#if defined (ARM_MATH_LOOPUNROLL)

#if defined (ARM_MATH_DSP)
	q31_t inA1, inA2, inB1, inB2;                  /* Temporary input variables */
	q15_t out1, out2, out3, out4;                  /* Temporary output variables */
	q31_t mul1, mul2, mul3, mul4;                  /* Temporary variables */
#endif

	/* Loop unrolling: Compute 4 outputs at a time */
	blkCnt = blockSize >> 2U;

	while (blkCnt > 0U) {
		/* C = A * B */

#if defined (ARM_MATH_DSP)
		/* read 2 samples at a time from sourceA */
		inA1 = read_q15x2_ia((q15_t **) &pSrcA);
		/* read 2 samples at a time from sourceB */
		inB1 = read_q15x2_ia((q15_t **) &pSrcB);
		/* read 2 samples at a time from sourceA */
		inA2 = read_q15x2_ia((q15_t **) &pSrcA);
		/* read 2 samples at a time from sourceB */
		inB2 = read_q15x2_ia((q15_t **) &pSrcB);

		/* multiply mul = sourceA * sourceB */
		mul1 = (q31_t)((q15_t)(inA1 >> 16) * (q15_t)(inB1 >> 16));
		mul2 = (q31_t)((q15_t)(inA1) * (q15_t)(inB1));
		mul3 = (q31_t)((q15_t)(inA2 >> 16) * (q15_t)(inB2 >> 16));
		mul4 = (q31_t)((q15_t)(inA2) * (q15_t)(inB2));

		/* saturate result to 16 bit */
		out1 = (q15_t) __SSAT(mul1 >> 15, 16);
		out2 = (q15_t) __SSAT(mul2 >> 15, 16);
		out3 = (q15_t) __SSAT(mul3 >> 15, 16);
		out4 = (q15_t) __SSAT(mul4 >> 15, 16);

		/* store result to destination */
#ifndef ARM_MATH_BIG_ENDIAN
		write_q15x2_ia(&pDst, __PKHBT(out2, out1, 16));
		write_q15x2_ia(&pDst, __PKHBT(out4, out3, 16));
#else
		write_q15x2_ia(&pDst, __PKHBT(out1, out2, 16));
		write_q15x2_ia(&pDst, __PKHBT(out3, out4, 16));
#endif /* #ifndef ARM_MATH_BIG_ENDIAN */

#else
		*pDst++ = (q15_t) __SSAT((((q31_t)(*pSrcA++) * (*pSrcB++)) >> 15), 16);
		*pDst++ = (q15_t) __SSAT((((q31_t)(*pSrcA++) * (*pSrcB++)) >> 15), 16);
		*pDst++ = (q15_t) __SSAT((((q31_t)(*pSrcA++) * (*pSrcB++)) >> 15), 16);
		*pDst++ = (q15_t) __SSAT((((q31_t)(*pSrcA++) * (*pSrcB++)) >> 15), 16);
#endif

		/* Decrement loop counter */
		blkCnt--;
	}

	/* Loop unrolling: Compute remaining outputs */
	blkCnt = blockSize % 0x4U;

#else

	/* Initialize blkCnt with number of samples */
	blkCnt = blockSize;

#endif /* #if defined (ARM_MATH_LOOPUNROLL) */

	while (blkCnt > 0U) {
		/* C = A * B */

		/* Multiply inputs and store result in destination buffer. */
		*pDst++ = (q15_t) __SSAT((((q31_t)(*pSrcA++) * (*pSrcB++)) >> 15), 16);

		/* Decrement loop counter */
		blkCnt--;
	}

}
#endif /* defined(ARM_MATH_MVEI) */

/**
  @} end of BasicMult group
 */
